This application is based on Japanese Patent Applications No. 2000-127226 filed on Apr. 27, 2000 and No. 2000-153140 filed on May 24, 2000 the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a stator of a rotary electric machine.
2. Description of Related Art
JP-A-11-299153 discloses an alternator for a vehicle which has a stator with curled coil ends. The portions of the coil, disposed between slots which are spaced apart by a predetermined pitch, are curled and twisted in a radial direction at the center. Therefore, all curled portions of the coil are circumferentially arranged side by side. In this arrangement, it is difficult to arrange the curled portions to avoid collisions with other portions, since the coil is widened at the curled portions especially when a thick coil wire is used.
JP-B-2927288 and JP-A-11-164506 disclose alternators for a vehicle having stator windings which are made of a plurality of segments welded to each other. In this arrangement, the welded portions require a complicated manufacturing process and an additional insulating process.
The present invention addresses these drawbacks by providing an improved stator arrangement and an improved manufacturing method.
It is therefore an object of this invention to provide an improved stator of a rotary electric machine.
It is a further object of this invention to provide a stator of a rotary electric machine which has a novel arrangement of windings.
According to a first aspect of the present invention, the stator of the rotary electric machine comprises a plurality of sub-winding sets. Each sub-winding set comprises a plurality of phase windings. Each of the phase windings is made of a continuous wire providing an individual coil on a stator core. The phase windings in the same phase are connected via connecting portions provided outside of the stator core. The turn portions are arranged on each of the sub-winding sets. Therefore, it is possible to avoid collisions between the turn portions. The continuous wire is capable of reducing connections on the poly-phase winding.
In the present invention, the phase winding may have at least three straight portions and two turn portions which are provided by the continuous wire.
The sub-winding sets can be mounted on the stator core by shrinking the sub-winding sets, inserting the shrunken sub-winding sets into a cavity of the stator core and expanding the shrunken sub-winding sets.
According to the another aspect of the present invention, a stator of a rotary electric machine comprises a poly-phase winding comprising a plurality of phase windings. Each of the phase windings is made of a continuous wire. The turn portions of each windings are arranged side by side with respect to a radial direction on one side of the stator core. It is possible to avoid collisions between the turn portions since the turn portions are arranged side by side. The continuous wire reduces the number of connections on the poly-phase winding.
The poly-phase winding may be formed by preparing a poly-phase wave winding having first turn portions, and forming at least two straight portions and a second turn portion between them on each of the middle portions of the poly-phase wave winding. The second turn portions may be formed by folding the wave winding at a predetermined position and shifting the straight portions placed on both sides of the predetermined position by a predetermined magnetic pole pitch. The straight portions may be shifted before folding.